Maintaining proper mechanics tha

ABSTRACT

A prosthetic hip joint is disclosed. The prosthetic hip joint includes a femoral component, which further includes a femoral head with a femoral head cavity and an acetabular component. The acetabular component includes an acetabular cup and an acetabular cup insert. The acetabular cup insert and the acetabular cup each has a through hole, where the through holes overlap a location of a native femoral head ligament.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of pending U.S. patent applicationSer. No. 15/292,825, which was filed on Oct. 13, 2016, which is adivisional of U.S. patent application Ser. No. 14/700,988, which wasfiled on Apr. 30, 2015, which is a continuation of U.S. patentapplication Ser. No. 13/034,226, now U.S. Pat. No. 9,023,112, which wasfiled on Feb. 24, 2011, the disclosures of which are hereby incorporatedby reference.

RELATED ART Field of the Invention

The present disclosure relates to orthopedic hip implants, componentsthereof, and methods of preparing native tissue for implantation of aforeign object, as well as methods of implanting foreign objects such asorthopedic hips and components thereof.

Brief Discussion of Related Art

A common problem in artificial hips is dislocation resulting from theball of the femoral head no longer being fully seated within theacetabular cup. Dislocation is particularly problematic immediatelyafter artificial hip replacement or revision surgery. As those skilledin the art are aware, soft tissues surrounding the natural joint aredamaged or removed during surgery in order to make way for thereplacement orthopedic implant. Even in circumstances of artificialjoint revision surgery, soft tissues are damaged to gain access to theartificial joint.

Dislocation is problematic in numerous respects. First, dislocationcreates obvious kinematic problems as the joint components are notaligned to function as designed or intended. Second, dislocation usuallyresults in joint pain from the unintended loads placed on surroundingtissues. Third, dislocation usually results in swelling of tissuessurrounding the joint. Fourth, dislocation can create “popping” soundsthat correlate with the ball entering and exiting the cup repetitively.Fifth, dislocation causes moments to be created in the joint. Sixth,dislocation leads to premature wear of the cup and/or femoral head,thereby increasing the likelihood of joint failure or loosening of thejoint.

Many hypothesizes exist as to the cause of dislocation as well asmethods and devices to reduce or inhibit dislocation. For example,certain orthopedic hip joints include permanent retention rings to lockthe femoral head into the acetabular cup. But these retention rings comeat a price—decreased range of motion. As the age of patients undergoingjoint replacement and revision surgeries drops and activity level ofolder adults increases, decreased range of motion is not a trade-offmost patients are willing to make to inhibit dislocation.

Another problem with existing THA is the incidence of femoral headseparation within the acetabular cup, leading to the femoral headsliding out in the superior-lateral direction and then back in theinferior-medial direction. This incidence of sliding of the femoral headwithin the acetabular cup leads to the observation that present day THAdo not function as a revolute joint, but rather have induced undesirableshear forces that do not exist in the native hip joint. This inducementof femoral head separation may be a main reason for the occurrence ofhip dislocation.

Introduction

It is a first aspect of the present invention to provide an orthopedichip joint comprising: (a) an implantable femoral component having afirst resonant frequency; (b) an implantable acetabular component havinga second resonant frequency; and, (c) a vibrational damper mounted to atleast one of the implantable femoral component and the implantableacetabular component, where a frequency resulting from interactionbetween the femoral component and the acetabular component approximatesa resonant frequency of at least one of a femur, a pelvis, andconnective tissue around a hip joint.

In a more detailed embodiment of the first aspect, the implantablefemoral component includes a femoral stem, a femoral neck, and a femoralhead, the femoral neck is separable from the femoral head and, thevibrational dampener comprises at least a portion of the femoral neck.In yet another more detailed embodiment, the implantable femoralcomponent includes a femoral stem, a femoral neck, and a femoral head,the femoral neck is separable from the femoral head and, the vibrationaldampener interposes the femoral neck and the femoral head. In a furtherdetailed embodiment, the implantable femoral component includes afemoral stem, a femoral neck, and a femoral head and, the vibrationaldampener comprises a sleeve wrapped around the femoral stem. In still afurther detailed embodiment, the implantable acetabular componentincludes an acetabular cup and an acetabular cup insert and, thevibrational dampener interposes the acetabular cup and the acetabularcup insert. In a more detailed embodiment, the implantable acetabularcomponent includes an acetabular cup and an acetabular cup insert and,the vibrational dampener is mounted to a bone side of the acetabularcup. In a more detailed embodiment, the vibrational damper comprises atleast one of silicone rubber, elastic silicone rubber, gutta percha,saline rubber, gore-tex, polystyrene, polytetrafluoroethylene, nylon,polyethylene, polyester, silk, polyethylene teraphthalate, and polyvinylalcohol-hydrogel.

It is a second aspect of the present invention to provide a method ofreducing propagation of vibrations through at least one component of anorthopedic hip joint, the method comprising mounting a vibrationaldamper to at least one of a femoral component and an acetabularcomponent of an orthopedic hip joint.

In a more detailed embodiment of the second aspect, the femoralcomponent includes a femoral stem, a femoral neck, and a femoral headand, the vibrational dampener comprises a sleeve wrapped around thefemoral stem. In yet another more detailed embodiment, the femoralcomponent includes a femoral stem, a femoral neck, and a femoral headand, the vibrational dampener interposes the femoral neck and femoralhead. In a further detailed embodiment, the acetabular componentincludes an acetabular cup and an acetabular cup insert and, thevibrational dampener interposes the acetabular cup and the acetabularcup insert. In still a further detailed embodiment, the acetabularcomponent includes an acetabular cup and an acetabular cup insert and,the vibrational dampener is mounted to a bone side of the acetabularcup.

It is a third aspect of the present invention to provide an orthopedichip joint comprising: (a) an implantable femoral component includes afirst magnet exhibiting a first magnetic field; and, (b) an implantableacetabular component includes a second magnet exhibiting a secondmagnetic field.

In a more detailed embodiment of the third aspect, the implantablefemoral component includes a femoral stem, a femoral neck, and a femoralhead, the femoral head includes the first magnet and, the first magnetis oriented so that upon implantation its positive pole is nearer thesecond magnet than a negative pole of the first magnet. In yet anothermore detailed embodiment, the implantable acetabular component includesan acetabular cup and an acetabular cup insert and, the second magnet isoriented so that upon implantation its negative pole is nearer thepositive pole of the first magnet than is a positive pole of the secondmagnet. In a further detailed embodiment, the implantable acetabularcomponent includes an acetabular cup and an acetabular cup insert and,the second magnet is oriented so that upon implantation its positivepole is nearer the positive pole of the first magnet than is a negativepole of the second magnet. In still a further detailed embodiment, theimplantable femoral component includes a femoral stem, a femoral neck,and a femoral head, the femoral head includes the first magnet and, thefirst magnet is oriented so that upon implantation its negative pole isnearer the second magnet than a positive pole of the first magnet. In amore detailed embodiment, the implantable acetabular component includesan acetabular cup and an acetabular cup insert and, the second magnet isoriented so that upon implantation its negative pole is nearer thenegative pole of the first magnet than is a positive pole of the secondmagnet. In a more detailed embodiment, the implantable acetabularcomponent includes an acetabular cup and an acetabular cup insert and,the second magnet is oriented so that upon implantation its positivepole is nearer the negative pole of the first magnet than is a negativepole of the second magnet. In another more detailed embodiment, theacetabular component comprises an acetabular cup and an acetabular cupinsert and, the second magnet is part of the acetabular cup. In yetanother more detailed embodiment, the acetabular component comprises anacetabular cup and an acetabular cup insert and, the second magnet ispart of the acetabular cup insert. In still another more detailedembodiment, the acetabular component comprises an acetabular cup and anacetabular cup insert, the acetabular component includes a plurality ofmagnets, where the plurality of magnets include the second magnet and,at least two of the plurality of magnets are oriented so that a negativepole of each magnet is upon implantation closer to a femoral head of thefemoral component than is a positive pole of each magnet.

In yet another more detailed embodiment of the third aspect, the atleast two of the plurality of magnets are symmetrically oriented withrespect to an axis extending through the acetabular component. In stillanother more detailed embodiment, the at least two of the plurality ofmagnets are asymmetrically oriented with respect to an axis extendingthrough the acetabular component. In a further detailed embodiment, theacetabular component comprises an acetabular cup and an acetabular cupinsert, the acetabular component includes a plurality of magnets, wherethe plurality of magnets include the second magnet and, at least two ofthe plurality of magnets are oriented so that a positive pole of eachmagnet is upon implantation closer to a femoral head of the femoralcomponent than is a negative pole of each magnet. In still a furtherdetailed embodiment, the at least two of the plurality of magnets aresymmetrically oriented with respect to an axis extending through theacetabular component. In a more detailed embodiment, the at least two ofthe plurality of magnets are asymmetrically oriented with respect to anaxis extending through the acetabular component.

It is a fourth aspect of the present invention to provide a method ofdecreasing impact forces between orthopedic hip joint components, themethod comprising: (a) associating a first magnetic field with a femoralcomponent of an orthopedic joint, the first magnetic field having apositive pole and a negative pole; and, (b) associating a secondmagnetic field with an acetabular component of the orthopedic joint, thesecond magnetic field having a positive pole and a negative pole, whereat least one of the positive poles and the negative poles are nearer oneanother than is the other of the positive poles and the negative poles.

In a more detailed embodiment of the fourth aspect, the act ofassociating the first magnetic field with the femoral component includesincluding a magnet as part of a femoral head, the magnet of the femoralhead is oriented so the positive pole is nearer the acetabular componentthan is the negative pole, the act of associating the second magneticfield with the acetabular component includes including a magnet as partof at least one of an acetabular cup and an acetabular cup insert and,the magnet of the acetabular component is oriented so the positive poleis nearer the positive pole of the magnet of the femoral component thanis the negative pole. In yet another more detailed embodiment, the actof associating the first magnetic field with the femoral componentincludes including a magnet as part of a femoral head, the magnet of thefemoral head is oriented so the negative pole is nearer the acetabularcomponent than is the positive pole, the act of associating the secondmagnetic field with the acetabular component includes including a magnetas part of at least one of an acetabular cup and an acetabular cupinsert and, the magnet of the acetabular component is oriented so thenegative pole is nearer the positive pole of the magnet of the femoralcomponent than is the positive pole. In a further detailed embodiment,the magnet of the femoral component is part of the acetabular cup. Instill a further detailed embodiment, the magnet of the femoral componentis part of the acetabular cup insert. In a more detailed embodiment, thestep of associating a second magnetic field with the acetabularcomponent of the orthopedic joint includes establishing a plurality ofpositive poles and a plurality of negative poles.

It is a fifth aspect of the present invention to provide a method ofretarding dislocation between a femoral component and an acetabularcomponent of an orthopedic hip joint, the method comprising: (a)associating a first magnetic field with a femoral component of anorthopedic joint, the first magnetic field having a positive pole and anegative pole; and, (b) associating a second magnetic field with anacetabular component of the orthopedic joint, the second magnetic fieldhaving a positive pole and a negative pole, where an attraction forcebetween one of the positive poles and one of the negative poles operatesto retard dislocation between the femoral component and the acetabularcomponent upon implantation.

In a more detailed embodiment of the fifth aspect, the act ofassociating the first magnetic field with the femoral component includesincluding a magnet as part of a femoral head, the magnet of the femoralhead is oriented so the positive pole is nearer the acetabular componentthan is the negative pole, the act of associating the second magneticfield with the acetabular component includes including a magnet as partof at least one of an acetabular cup and an acetabular cup insert and,the magnet of the acetabular component is oriented so the negative poleis nearer the positive pole of the magnet of the femoral component thanis the positive pole. In yet another more detailed embodiment, the actof associating the first magnetic field with the femoral componentincludes including a magnet as part of a femoral head, the magnet of thefemoral head is oriented so the negative pole is nearer the acetabularcomponent than is the positive pole, the act of associating the secondmagnetic field with the acetabular component includes including a magnetas part of at least one of an acetabular cup and an acetabular cupinsert and, the magnet of the acetabular component is oriented so thepositive pole is nearer the negative pole of the magnet of the femoralcomponent than is the negative pole. In a further detailed embodiment,the magnet of the femoral component is part of the acetabular cup. Instill a further detailed embodiment, the magnet of the femoral componentis part of the acetabular cup insert. In a more detailed embodiment, thestep of associating a second magnetic field with the acetabularcomponent of the orthopedic joint includes establishing a plurality ofpositive poles and a plurality of negative poles.

It is a sixth aspect of the present invention to provide a prosthetichip joint comprising: (a) a femoral component including a femoral head;and, (b) an acetabular component including an acetabular cup and anacetabular cup insert, the acetabular cup insert sized to receive thefemoral head, where the femoral head is sized to have a spherical centerthat matches a spherical center of a patient's native femoral head,where the acetabular cup is sized to have a cavity with a sphericalcenter that matches a spherical center of a cavity of a patient's nativeacetabulum and, where the femoral head center of the femoral componentis concentric with the center of the cavity of the acetabular cup.

In a more detailed embodiment of the sixth aspect, the spherical centerof the patient's native femoral head is determined from the interface ofthe native femoral head with the native acetabulum during walking. Inyet another more detailed embodiment, the spherical center of thepatient's native acetabulum is determined from the interface of thenative femoral head with the native acetabulum during walking. In afurther detailed embodiment, the patient's native femoral head includescartilage mounted to the native femoral head. In still a furtherdetailed embodiment, the cavity of the patient's native acetabulumincludes cartilage mounted to the native acetabulum. In a more detailedembodiment, a radial thickness of the acetabular cup is nonuniform alonga circumferential length. In a more detailed embodiment, a radialthickness of the femoral head is nonuniform along a circumferentiallength. In another more detailed embodiment, an outer aspect of theacetabular cup is nonspherical and an inner aspect of the acetabular cupis spherical. In yet another more detailed embodiment, an outer aspectof the acetabular cup is spherical and an inner aspect of the acetabularcup is nonspherical.

It is a seventh aspect of the present invention to provide a method ofdesigning an orthopedic hip joint implant, the method comprising: (a)conducting a kinematic analysis of a population eligible for hipreplacement surgery; (b) establishing contact points between a nativefemur and a native acetabulum for each person in the population usingthe kinematic analysis; (c) creating an imaginary sphere that correlateswith the contact points for each person in the population; (d)determining a dimension of the imaginary sphere for each person in thepopulation including at least one of radius, diameter, circumference,and center point; and, (e) designing at least one of a femoral componentand an acetabular component using the dimension of the imaginary spherefor each person in the population.

In a more detailed embodiment of the seventh aspect, the determiningstep includes determining the center point of the imaginary sphere,where the center point represents the anatomical spherical center and,the designing step includes designing the femoral component to have afemoral ball with a spherical curvature, the spherical curvaturecorresponding to an imaginary prosthetic sphere having a center that isthe same as the anatomical spherical center. In yet another moredetailed embodiment, the population comprises a single person. In afurther detailed embodiment, the population comprises a plurality ofpersons having at least one common trait taken from the group of age,gender, race, height, bone size. In still a further detailed embodiment,the conducting step includes observing a hip joint of each person in thepopulation, where the observation takes place while the hip joint isunder weight-bearing stress. In a more detailed embodiment, theobservation includes using at least one of fluoroscopy, magneticresonance imaging, CT imaging, ultrasound. In a more detailedembodiment, the conducting step includes observing a hip joint of eachperson in the population and, the conducting step includes creating athree dimensional model of the hip joint for each person in thepopulation. In another more detailed embodiment, the establishing stepincludes utilizing a collision detection analysis to establish thecontact points between the native femur and the native acetabulum foreach person in the population using the three dimensional model of thehip joint. In yet another more detailed embodiment, the inventionfurther includes mapping a location of the imaginary sphere for eachperson in the population with respect to boney landmarks.

It is a ninth aspect of the present invention to provide a method offabricating an orthopedic hip joint, the method comprising: (a)conducting a kinematic analysis of a population eligible for hipreplacement surgery; (b) establishing contact points between a nativefemur and a native acetabulum for each person in the population usingthe kinematic analysis; (c) creating a sphere that correlates with thecontact points for each person in the population; (d) determining adimension of the sphere for each person in the population including atleast one of radius, diameter, circumference, and center point; (e)designing at least one of a femoral component and an acetabularcomponent using the dimension of the sphere for each person in thepopulation; and, (f) fabricating at least one of the femoral componentand the acetabular component.

In a more detailed embodiment of the ninth aspect, the determining stepincludes determining the center point of the imaginary sphere, where thecenter point represents the anatomical spherical center and, thedesigning step includes designing the femoral component to have afemoral ball with a spherical curvature, the spherical curvaturecorresponding to an imaginary prosthetic sphere having a center that isthe same as the anatomical spherical center. In yet another moredetailed embodiment, the population comprises a single person. In afurther detailed embodiment, the population comprises a plurality ofpersons having at least one common trait taken from the group of age,gender, race, height, bone size. In still a further detailed embodiment,the conducting step includes observing a hip joint of each person in thepopulation, where the observation takes place while the hip joint isunder weight-bearing stress. In a more detailed embodiment, theobservation includes using at least one of fluoroscopy, magneticresonance imaging, CT imaging, ultrasound. In a more detailedembodiment, the conducting step includes observing a hip joint of eachperson in the population and, the conducting step includes creating athree dimensional model of the hip joint for each person in thepopulation. In another more detailed embodiment, the establishing stepincludes utilizing a collision detection analysis to establish thecontact points between the native femur and the native acetabulum foreach person in the population using the three dimensional model of thehip joint. In yet another more detailed embodiment, the inventionfurther includes mapping a location of the imaginary sphere for eachperson in the population with respect to boney landmarks.

It is a tenth aspect of the present invention to provide an acetabularcup comprising a bowl-shaped wall at least partially delineating aconcavity, the bowl-shaped wall including a top perimeter demarcating afirst opening through the bowl-shaped wall, the bowl-shaped wall alsodemarcating a second opening sized to allow throughput of at least aportion of a femoral head ligament.

In a more detailed embodiment of the tenth aspect, the invention alsoincludes at least one tab operatively coupled to the wall, the at leastone tab including a through hole. In yet another more detailedembodiment, the invention also includes a plurality of tabscircumferentially distributed about the top perimeter of the wall, eachof the plurality of tabs having a through hole. In a further detailedembodiment, the invention also includes a plurality of guide pins eachsized to allow insertion into the through hole of each tab.

It is an eleventh aspect of the present invention to provide a femoralcomponent of a prosthetic hip joint comprising a femoral stem adapted tobe inserted into the intramedullary canal of a femur, the femoral stemcoupled to a femoral neck, the femoral neck extending proximally awayfrom the femoral stem, the femoral neck operatively coupled to a femoralball mounted to a proximal end of the femoral neck, where the femoralball includes a proximal cavity.

In a more detailed embodiment of the eleventh aspect, the proximalcavity of the femoral ball is a through hole extending through thefemoral ball. In yet another more detailed embodiment, the proximalcavity extends into the femoral neck. In a further detailed embodiment,the proximal cavity extends into the femoral stem. In still a furtherdetailed embodiment, the femoral stem, femoral neck, and femoral ballcomprise a single piece. In a more detailed embodiment, the proximalcavity has at least one of a circular cross-section, a rectangularcross-section, and an irregular cross-section.

It is a twelfth aspect of the present invention to provide a method ofmounting an acetabular component to a patient, the method comprising:(a) positioning and aligning an acetabular jig with respect to anacetabulum, where the acetabular jig includes a bowl-shaped wall havinga through hole accommodating throughput of a portion of a femoral headligament attached to the acetabulum; (b) drilling reference holesproximate the acetabulum using the acetabular jig as a guide; and, (c)inserting a pin into each reference hole, where the positioning andaligning step includes inserting the portion of the femoral headligament attached to the acetabulum through the through hole of theacetabular jig.

In a more detailed embodiment of the twelfth aspect, the method furtherincludes positioning a guide cup with respect to the pelvis using thepins, mounting a guide pin to the acetabulum while the guide cup is inposition and, removing the guide cup after the guide pin is mounted tothe acetabulum.

It is a thirteenth aspect of the present invention to provide aprosthetic hip joint comprising: (a) a femoral component including afemoral head with a femoral head cavity; and, (b) an acetabularcomponent including an acetabular cup and an acetabular cup insert, theacetabular cup insert and the acetabular cup each having a through hole,where the through holes overlap a location of a native femoral headligament.

In a more detailed embodiment of the thirteenth aspect, the femoral headcavity is sized to receive a portion of a native femur that remainsattached to the native femoral head ligament. In yet another moredetailed embodiment, the femoral head cavity extends into a neck of thefemoral component. In a further detailed embodiment, the femoral headcavity extends through a neck of the femoral component and into a shaftof the femoral component. In still a further detailed embodiment, thethrough holes of the acetabular cup and acetabular cup insert areoriented to align with a location where a femoral head ligament ismounted to an acetabulum.

It is a fourteenth aspect of the present invention to provide a methodof implanting an orthopedic hip joint, the method comprising: (a)implanting and mounting an acetabular component to a native acetabulum;(b) implanting and mounting a femoral component to a native femur; and,(c) maintaining a connection between a native femoral head ligament andat least one of the native acetabulum and the native femur afterimplanting and mounting the acetabular component and the femoralcomponent.

In a more detailed embodiment of the fourteenth aspect, the methodfurther includes reshaping a portion of a native femoral head attachedto the native femoral head ligament to create a femoral revision and,coupling the femoral component to the femoral revision. In yet anothermore detailed embodiment, the invention further includes severing thenative femoral head from the native femur, wherein the femoral revisioncomprises a femoral bone insert mounted to the native femoral headligament, and wherein the act of coupling the femoral component to thefemoral revision includes inserting the femoral bone insert into acavity of the femoral component. In a further detailed embodiment, thecavity extends into a neck of the femoral component. In still a furtherdetailed embodiment, the cavity extends through a neck of the femoralcomponent and into a shaft of the femoral component.

It is a fifteenth aspect of the present invention to provide a method ofimplanting at least one orthopedic hip joint component, the methodcomprising: (a) implanting and mounting at least one of an acetabularcomponent to a native acetabulum and a femoral component to a nativefemur; and, (b) maintaining a connection between a native femoral headligament and at least one of the native acetabulum and the native femur.

In a more detailed embodiment of the fifteenth aspect, the implantingact includes mounting the acetabular component to the native acetabulumand, the acetabular component includes a cup having an orifice throughwhich the native femoral head ligament extends. In yet another moredetailed embodiment, the implanting act includes mounting the femoralcomponent to the native femur and, the femoral component includes acavity to receive at least a portion of the native femur connected tothe native femoral head ligament. In a further detailed embodiment, theinvention further includes reshaping a portion of a native femoral headattached to the native femoral head ligament to create a femoralrevision, implanting and mounting the femoral component to the nativefemur and, coupling the femoral component to the femoral revision. Instill a further detailed embodiment, the invention further includessevering the native femoral head from the native femur, wherein thefemoral revision comprises a femoral bone insert, and wherein the act ofcoupling the femoral component to the femoral revision includesinserting the femoral bone insert into a cavity of the femoralcomponent. In a more detailed embodiment, the implanting act includesimplanting and mounting the acetabular component to the nativeacetabulum and, the implanting act includes implanting and mounting thefemoral component to the native femur. In a more detailed embodiment,the invention further includes mounting a first portion of a tether toat least one of the native acetabulum and the acetabular component, andmounting a second portion of the tether to at least one of the nativefemur and the femoral component.

It is a sixteenth aspect of the present invention to provide anacetabular component of a prosthetic hip joint comprising: (a) anacetabular cup adapted to be mounted to a native acetabulum; (b) a firstacetabular cup insert to be mounted to the acetabular cup andrepositionable with respect to the acetabular cup; and, (c) a secondacetabular cup insert to be mounted to the first acetabular cup insertand repositionable with respect to the first acetabular cup insert, thefirst acetabular cup insert interposing the second acetabular cup insertand the acetabular cup.

In a more detailed embodiment of the sixteenth aspect, the acetabularcup includes a circumferential groove on an interior surface thereof,the first acetabular cup includes a projection that is received withinthe circumferential groove and, the projection is repositionable withrespect to the circumferential groove. In yet another more detailedembodiment, the first acetabular cup insert includes a circumferentialgroove on an exterior surface thereof, the acetabular cup includes aprojection on an interior surface thereof and, the circumferentialgroove is repositionable with respect to the projection. In a furtherdetailed embodiment, the first acetabular cup insert includes acircumferential groove on an interior surface thereof, the secondacetabular cup includes a projection that is received within thecircumferential groove and, the projection is repositionable withrespect to the circumferential groove. In still a further detailedembodiment, the second acetabular cup insert includes a circumferentialgroove on an exterior surface thereof, the first acetabular cup insertincludes a projection on an interior surface thereof and, thecircumferential groove is repositionable with respect to the projection.In a more detailed embodiment, the first acetabular cup insert isslidably repositionable with respect to the acetabular cup within afirst plane, the first acetabular cup insert is slidably repositionablewith respect to the second acetabular cup insert within a second planeand, the first plane is generally perpendicular with respect to thesecond plane. In a more detailed embodiment, the first acetabular cupinsert is rotationally repositionable with respect to the acetabular cupand, the first acetabular cup insert is slidably repositionable withrespect to the second acetabular cup insert. In another more detailedembodiment, the first acetabular cup insert is slidably repositionablewith respect to the acetabular cup and, the first acetabular cup insertis rotationally repositionable with respect to the second acetabular cupinsert.

It is a seventeenth aspect of the present invention to provide a methodof assembling a mobile bearing acetabular component of a prosthetic hipjoint, the method comprising: (a) mounting a first acetabular cup insertto an acetabular cup, where mounting the first acetabular cup insert tothe acetabular cup includes repositioning the first acetabular cupinsert with respect to the acetabular cup without disengaging the firstacetabular cup insert from the acetabular cup; and, (b) mounting asecond acetabular cup insert to the first acetabular cup insert, wheremounting the second acetabular cup insert to the first acetabular cupincludes repositioning the second acetabular cup insert with respect tothe first acetabular cup insert without disengaging the secondacetabular cup insert from the first acetabular cup insert.

In a more detailed embodiment of the seventeenth aspect, repositioningthe first acetabular cup insert with respect to the acetabular cupincludes sliding the first acetabular cup insert against the acetabularcup and, repositioning the second acetabular cup insert with respect tothe first acetabular cup insert includes sliding the second acetabularcup insert against the first acetabular cup insert. In yet another moredetailed embodiment, repositioning the first acetabular cup insert withrespect to the acetabular cup includes rotating the first acetabular cupinsert against the acetabular cup and, repositioning the secondacetabular cup insert with respect to the first acetabular cup insertincludes sliding the second acetabular cup insert against the firstacetabular cup insert. In a further detailed embodiment, repositioningthe first acetabular cup insert with respect to the acetabular cupincludes sliding the first acetabular cup insert against the acetabularcup and, repositioning the second acetabular cup insert with respect tothe first acetabular cup insert includes rotating the second acetabularcup insert against the first acetabular cup insert.

It is an eighteenth aspect of the present invention to provide anacetabular component of a prosthetic hip joint comprising: (a) anacetabular cup adapted to be mounted to a native acetabulum; and, (b) afirst acetabular cup insert to be mounted to the acetabular cup andrepositionable with respect to the acetabular cup, the first acetabularcup insert is concurrently repositionable deeper into an interior of theacetabular cup and repositionable outside of an outline of theacetabular cup.

In a more detailed embodiment of the eighteenth aspect, the acetabularcup includes a circumferential groove on an interior surface thereof,the first acetabular cup includes a projection that is received withinthe circumferential groove and, the projection is repositionable withrespect to the circumferential groove. In yet another more detailedembodiment, the first acetabular cup insert includes a circumferentialgroove on an exterior surface thereof, the acetabular cup includes aprojection on an interior surface thereof and, the circumferentialgroove is repositionable with respect to the projection.

It is a nineteenth aspect of the present invention to provide a methodof assembling a mobile bearing acetabular component of a prosthetic hipjoint, the method comprising mounting a first acetabular cup insert toan acetabular cup, where mounting the first acetabular cup insert to theacetabular cup includes concurrently repositioning the first acetabularcup insert deeper into an interior of the acetabular cup andrepositioning the first acetabular cup insert outside of an outline ofthe acetabular cup.

In a more detailed embodiment of the nineteenth aspect, repositioningthe first acetabular cup insert with respect to the acetabular cupincludes sliding the first acetabular cup insert against the acetabularcup.

It is a twentieth aspect of the present invention to provide a method ofrevising a proximal aspect of a native femur to receive a femoralcomponent of a prosthetic hip joint, the method comprising: (a) removinga native femoral head from a native femur; (b) reshaping a neck of thenative femur; and, (c) mounting a prosthetic femoral component onto thereshaped neck.

In a more detailed embodiment of the twentieth aspect, the prostheticfemoral component comprises a femoral ball. In yet another more detailedembodiment, the prosthetic femoral component comprises a femoral balland a femoral neck sleeve. In a further detailed embodiment, the femoralneck sleeve is cylindrical. In still a further detailed embodiment, thefemoral neck sleeve is frustoconical.

It is a twenty-first aspect of the present invention to provide anorthopedic hip joint comprising: (a) an implantable femoral componenthaving a first resonant frequency; and, (b) an implantable acetabularcomponent having a second resonant frequency, where a frequencyresulting from interaction between the femoral component and theacetabular component is different from a resonant frequency of at leastone of a femur, a pelvis, and connective tissue around a hip joint.

In a more detailed embodiment of the twenty-first aspect, theimplantable femoral component includes a femoral stem, a femoral neck,and a femoral head and, the femoral neck is separable from the femoralhead. In yet another more detailed embodiment, the implantableacetabular component includes an acetabular cup and an acetabular cupinsert.

It is a twenty-second aspect of the present invention to provide amethod of designing an orthopedic hip joint, the method comprising: (a)creating an implantable femoral component having a first resonantfrequency; and, (b) creating an implantable acetabular component havinga second resonant frequency, where a frequency resulting frominteraction between the femoral component and the acetabular componentis different from a resonant frequency of at least one of a femur, apelvis, and connective tissue around a hip joint.

In a more detailed embodiment of the twenty-second aspect, the femoralcomponent includes a femoral stem, a femoral neck, and a femoral head.In yet another more detailed embodiment, the acetabular componentincludes an acetabular cup and an acetabular cup insert.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an elevated perspective view of a first exemplary prosthetichip joint in accordance with the instant disclosure, shown with a ghostimage of the patient's natural anatomy.

FIG. 2 is an elevated perspective view of the first exemplary prosthetichip joint of FIG. 1, shown with a stem damper.

FIG. 3 is an elevated perspective view of the first exemplary prosthetichip joint of FIG. 1, shown with an acetabular cup damper.

FIG. 4 is an elevated perspective view of the first exemplary prosthetichip joint of FIG. 1, shown with an acetabular cup insert damper.

FIG. 5 is an elevated perspective view of a second exemplary prosthetichip joint in accordance with the instant disclosure, shown with a ghostimage of the patient's natural anatomy.

FIG. 6 is an elevated perspective view of an alternate exemplaryprosthetic hip joint, shown with indicia indicating like magnetic fieldsto repel certain components.

FIG. 7 is an elevated perspective view of another alternate exemplaryprosthetic hip joint, shown with a ghost image of the patient's naturalanatomy.

FIG. 8 is a profile view of a human pelvis and proximal femur showingconcentric anatomical spheres.

FIG. 9 is a frontal view of a human pelvis and proximal femur showingconcentric anatomical spheres.

FIG. 10 is a frontal view of a human pelvis and proximal femur showingnon-concentric anatomical spheres.

FIG. 11 is a profile view of a human pelvis and proximal femur showingnon-concentric anatomical spheres.

FIG. 12 is a frontal view of a human pelvis and proximal femur showingnon-concentric anatomical spheres.

FIG. 13 is a frontal view of a human pelvis and proximal femur showingnon-concentric anatomical spheres.

FIG. 14 is a profile view of a human proximal femur showing ananatomical sphere that is correctly selected.

FIG. 15 is a profile view of a human pelvis showing an anatomical spherethat is correctly selected.

FIG. 16 is a profile view of a human pelvis and proximal femur showing acommon anatomical sphere center.

FIG. 17 is a frontal view of a human pelvis and proximal femur showing acommon anatomical sphere center.

FIG. 18 is an X-ray image of a preexisting hip implant failing to haveconcentric centers.

FIG. 19 is another X-ray image of a different preexisting hip implantfailing to have concentric centers.

FIG. 20 is a diagram of the proximal femur and acetabulum of the pelvis.

FIG. 21 is a profile view of a pelvis showing a femoral head ligamentextending from and attached to the acetabulum.

FIG. 22 is an overhead view of a landmark cup in accordance with theinstant disclosure shown prior to insertion into the acetabulum.

FIG. 23 is an overhead view of the landmark cup of FIG. 22, shownsubsequent to insertion into the acetabulum.

FIG. 24 is an overhead view of the landmark cup of FIG. 22, shownsubsequent to insertion into the acetabulum and with the pins inserted.

FIG. 25 is a profile view of the acetabulum after the landmark cup hasbeen removed.

FIG. 26 is an overhead view of an exemplary guide pin cup and guide pinused to orient a reamer reaming the acetabulum.

FIG. 27 is a profile view of a reamed acetabulum.

FIG. 28 is an overhead view of a permanent acetabular cup mounted to thepelvis.

FIG. 29 is an overhead view of the permanent acetabular cup of FIG. 28,with the guide pins removed.

FIG. 30 is a profile view of a natural human hip joint.

FIG. 31 is a profile view showing a femoral aspect of a furtherexemplary hip joint in accordance with the instant disclosure, whileattached to the native pelvis.

FIG. 32 is a profile view showing the femoral aspect and an acetabularcomponent of the further exemplary hip joint in accordance with theinstant disclosure, while attached to the native pelvis.

FIG. 33 is a profile view showing the femoral aspect of the furtherexemplary hip joint, prior to insertion into a femoral component.

FIG. 34 is a profile view showing the femoral component, femoral aspect,and an acetabular component of the further exemplary hip joint, whileattached to the native pelvis and femur.

FIG. 35 is a profile view showing an even further exemplary hip joint,while attached to the native pelvis and femur.

FIG. 36 includes an elevated perspective view of an exemplary acetabularcup and a bottom view of an exemplary acetabular cup insert.

FIG. 37 comprises two perspective views showing some of the movementpossible between the acetabular cup and acetabular cup insert of FIG.36.

FIG. 38 is a perspective view of the acetabular cup and acetabular cupinsert of FIG. 36, shown mounted to a pelvis.

FIG. 39 includes a top view of an exemplary acetabular cup, a top viewof an intermediate liner, and a bottom view of an exemplary acetabularcup insert.

FIG. 40 are perspective views of the acetabular cup, acetabular liner,and acetabular cup insert of FIG. 39, shown mounted to a pelvis.

FIG. 41 includes a top view of an exemplary acetabular cup, a top viewof an intermediate liner, and a bottom view of an exemplary acetabularcup insert.

FIG. 42 includes comparison views of a femoral head prior to reshapingof the femoral neck.

FIG. 43 includes comparison views of a femoral head prior to reshapingof the femoral neck in mounting thereto a cylindrical sleeve.

FIG. 44 includes comparison views of a femoral head prior to reshapingof the femoral neck in mounting thereto a conical sleeve.

FIG. 45 is a vertical cross-section of a present day acetabular cup orcup insert having a uniform wall thickness.

FIG. 46 is an overhead view of an acetabulum shown with variousreference markings, A-E.

FIG. 47 is a vertical cross-section of an exemplary acetabular cup orcup insert that has a non-uniform wall thickness and shape.

FIG. 48 are vertical cross-sections of exemplary acetabular cups or cupinserts that have a non-uniform wall thickness and shape.

FIG. 49 are vertical cross-sections of present day acetabular cups orcup inserts shown with an attached insert to shift the spherical centerof the acetabular component.

DETAILED DESCRIPTION

The exemplary embodiments of the present disclosure are described andillustrated below to encompass orthopedic hip implants, componentsthereof, and methods of preparing native tissue for implantation of aforeign object, as well as methods of implanting foreign objects such asorthopedic hips and components thereof. Of course, it will be apparentto those of ordinary skill in the art that the preferred embodimentsdiscussed below are exemplary in nature and may be reconfigured withoutdeparting from the scope and spirit of the present invention. However,for clarity and precision, the exemplary embodiments as discussed belowmay include optional steps, methods, and features that one of ordinaryskill should recognize as not being a requisite to fall within the scopeof the present invention.

Referring to FIG. 1, a first exemplary prosthetic hip joint 100 includesa femoral component 102 cooperating with an acetabular component 104. Inexemplary form, the femoral component 102 includes a femoral stem 106for implantation into the proximal intramedullary canal 110 of a femur112 in order to secure the femoral component to the femur. The femoralstem 106 may be fabricated from any feasible material, including metalssuch as, without limitation, titanium, cobalt chromium, and stainlesssteel. In this exemplary embodiment, the femoral stem 106 includes astem damper 120 to reduce vibrations transmitted between the femoralstem and the femur 112 that might contribute to loosening of the femoralstem within the intramedullary canal. More specifically, the exemplarystem damper 120 is wrapped around the femoral stem 106 so that thedamper interposes the stem and femur when implanted. In exemplary form,the damper 120 comprises a sleeve that may be fabricated from one ormore materials that are biologically compatible and reduce vibrationstransmitted between the femoral stem 106 and the femur 112 including,without limitation, silicone rubber, elastic silicone rubber, guttapercha, saline rubber, gore-tex, polystyrene, polytetrafluoroethylene,nylon, polyethylene, polyester, silk, polyethylene teraphthalate,polyvinyl alcohol-hydrogel. But this is not the only damper used as partof the first exemplary hip joint 100.

The stem damper 120 may also be inserted between a metal sleeve that isfixated with cement and/or a bone in-growth material, and the femoralstem 106. Therefore, the femoral stem 106 is locked into the metalsleeve and the damper 120 is inserted therebetween.

Referencing FIG. 2, the femoral component 102 (shown without the stemdamper 120) also includes a neck 130 coupled to the femoral stem 106. Inthis exemplary embodiment, the neck 130 includes a frustoconical end(not shown) that engages a corresponding frustoconical cavity (notshown) formed within a ball 136. In this exemplary embodiment, the ball136 may be fabricated from any feasible material, including metals andceramics such as, without limitation, titanium, cobalt chromium,stainless steel, and alumina. In order to reduce vibrations transmittedbetween the neck 130 and the ball 136, the frustoconical end includes adamper 140 that interposes the neck and ball. The exemplary damper 140comprises a cap that conforms to the shape of the frustoconical end.Alternatively, the damper 140 may be in the shape of a ring thatcircumscribes the neck 130 of the femoral component 102.

It should be noted that when the damper 140 is used, the frustoconicalcavity formed within the ball 136 is large enough to accommodate boththe cap and the frustoconical end. As with the foregoing damper, thisexemplary damper 140 may be fabricated from one or more materials thatare biologically compatible and reduce vibrations transmitted betweenthe neck 130 and the ball 136 including, without limitation, siliconerubber, elastic silicone rubber, gutta percha, saline rubber, gore-tex,polystyrene, polytetrafluoroethylene, nylon, polyethylene, polyester,silk, polyethylene teraphthalate, polyvinyl alcohol-hydrogel. Inaddition to the dampers 120, 140 associated with the femoral component102, the acetabular component 104 may also include its own dampers.

Referring to FIG. 3, the acetabular component 104 includes an acetabularcup 150 and an acetabular insert 152. The interior of the acetabular cup150 includes a semispherical cavity that receives a semispherical aspectof the acetabular insert 152. The acetabular cup 150 includes a damper160 that interposes the cup and a patient's pelvis 170. In thisexemplary embodiment, the acetabular cup 150 may be fabricated from anyfeasible material, including metals such as, without limitation,titanium, cobalt chromium, and stainless steel. In exemplary form, thedamper 160 is semicircular and is mounted to the rear of the acetabularcup 150. The overall area of this damper 150 can be very small, lessthan 1.0 mm² or can cover the full surface area of the acetabular cup.One or more dampers 150 may be used. By interposing the acetabular cup150 and the pelvis 170, vibrations transmitted between the cup andpelvis are reduced. It is believed that vibrations transmitted betweenthe cup 150 and pelvis 170 contribute to loosening of the cup and jointfailure. The exemplary damper 160 may be fabricated from one or morematerials that are biologically compatible and reduce vibrationstransmitted between the cup 150 and the pelvis 170 including, withoutlimitation, silicone rubber, elastic silicone rubber, gutta percha,saline rubber, gore-tex, polystyrene, polytetrafluoroethylene, nylon,polyethylene, polyester, silk, polyethylene teraphthalate, polyvinylalcohol-hydrogel.

Referencing FIG. 4, in order to reduce vibrations transmitted betweenthe acetabular component 104 and adjacent structures, a damper 180interposes the acetabular insert 152 and the acetabular cup 150 (shownwithout the damper 160). In this exemplary embodiment, the acetabularinsert 152 may be fabricated from any feasible material, includingmetals and ceramics such as, without limitation, titanium, cobaltchromium, stainless steel, and alumina. In exemplary form, the damper180 is semicircular and is mounted to the backside of the acetabularinsert 152. The overall area of this damper 180 may be very small, forexample less than 1.0 mm², or can cover the full surface area of theacetabular cup. Either one or more dampers can be used. By interposingthe acetabular cup 150 and the acetabular insert 152, vibrationstransmitted between the cup and insert are reduced. It is believed thatvibrations transmitted between the cup 150 and insert 152 contribute toloosening of the cup and joint failure. The exemplary damper 180 may befabricated from one or more materials that are biologically compatibleand reduce vibrations transmitted between the cup 150 and the insert 152including, without limitation, silicone rubber, elastic silicone rubber,gutta percha, saline rubber, gore-tex, polystyrene,polytetrafluoroethylene, nylon, polyethylene, polyester, silk,polyethylene teraphthalate, polyvinyl alcohol-hydrogel.

The exemplary vibrational dampers 120, 140, 160, 180 may be utilizedwhen the resonant frequencies of adjacent components are not the same.Due to the presence of hip separation and sliding of the femoral headwithin the acetabular cup, impulse loads and vibrational energy aretransmitted and propagated throughout the hip joint.

The natural or resonant frequency of an object is the frequency at whichthat object will vibrate freely. If a varying force with a frequencyequal to the natural frequency is applied to an object, the vibrationscan become violent, a phenomenon known as resonance. Resonance is thebuildup of large vibration amplitude that occurs when a structure or anobject is excited at its natural frequency. Resonance can be eitherdesirable or undesirable. In the context of acoustic resonance, adesirable resonance is exhibited by musical instruments. Conversely,undesirable resonance can lead to mechanical failures resulting inbridges collapsing and fracturing of aircraft wings.

The quality of the vibration and propagation of the vibration producedby a vibrating object is dependent upon the natural frequencies of thevibrational waves produced by the object. Some objects tend to vibrateat a single frequency, while other objects vibrate and produce morecomplex waves with a set of frequencies. If converted to a sound, theseobjects create sounds that could be described as noise. The actualfrequency at which an object will vibrate at is determined by thefollowing relationship: frequency=speed/wavelength. The inventor hasfound it beneficial to determine the natural frequency of THAimplantable components and secondary structures (e.g., bone cement) tomitigate undesirable resonance.

A first exemplary method for determining resonant frequency of acomponent or tissue includes excitation of the component or tissueusing, for example a speaker, amplifying different frequencies. Forexample, an accelerometer may be used on bones, attaching one tri-axialaccelerometer rigidly to the bone and then when excited, theacceleration signal, once filtered, is used to determine the naturalfrequency of the bone.

Also, a Fourier Series may be used to determine the frequency of anobject in question. The Fourier Series reveals how a mathematical seriesof sine and cosine terms can be used to analyze a waveform. Once theFourier Series is written for a waveform then the components of theseries completely describe the frequency content of the waveform. Thereare four conditions that must be met in order for the Fourier Series tobe useful.

-   -   1. The waveform must be periodic. This waveform must repeat time        for a Fourier Series to exist.    -   2. If the function has discontinuities, their number must be        finite in any period.    -   3. The function must contain a finite number of maxima and        minima during any period.    -   4. The function must be absolutely integrable in any period;        that is,

∫₀ ^(T) |x(t)|dt|∞

Where x(t) describes that function.The Fourier Series, in general is:

x(t)=α ₀ +α ₁ cos ω₀ t+α ₂ cos 2ω₀ t+ . . . α _(n) cos nω ₀ t+ . . . b₂sin ω₀ t+b ₂ sin 2ω₀ t+ . . . b _(n) sin nω ₀ t . . .

where the quantity ω_(o) is generally measured in radians per second,and is referred to as the circular frequency. Since the motion repeatsitself in 2π radians, then

ω 0 = 2   π τ = 2   π  0 ,

where τ and

are the period and frequency of the harmonic motion, usually measured insecond and cycles per second, respectively.

The Fourier Series can also be written in a more general form as:

${x(t)} = {\alpha_{n}{\sum\limits_{n = 1}^{\infty}\; {{( {{a_{n}\cos \; n\; \omega_{0}t} + {b_{n}\sin \; n\; \omega_{0}t}} ).}}}}$

First, ω_(o) is found from the period of x (t) and is equal to

2π/T (also

₀=1/T).

The □₀ coefficient is the DC (direct current) term and is equal to theaverage value of x(t) over one period. This is determined by

$a_{0} = {\frac{1}{T}{\int_{0}^{T}{{x(t)}{{dt}.}}}}$

The remaining coefficients, □_(n) and b_(n), are evaluated for n−1, 2,3, . . . by

${a_{n} = {\frac{2}{T}{\int_{0}^{T}{{x(t)}\cos \; n\; \omega_{0}^{t}\text{/}{dt}}}}},{and}$$b_{n} = {\frac{2}{T}{\int_{0}^{T}{{x(t)}\sin \; n\; \omega_{0}^{t}\text{/}{{dt}.}}}}$

Those skilled in the art may be familiar with numerous other methodsthat may be used to determine resonant frequencies for bodily tissue,implantable components, and secondary structures.

When a patient experiences hip separation, once the femoral head slidesback into the acetabular cup, an impulse load is been generated, whichresults in vibration being propagated throughout the hip joint. If thesevibrations are at or near resonant frequencies of bone, the implantedcomponents, and/or secondary structures, detrimental resonance can leadto premature failure. To reduce this premature failure and wear,vibrational dampers are positioned to absorb vibrations between adjacentcomponents.

In order to determine whether vibrational dampers 120, 140, 160, 180 maybe preferred, the exemplary orthopedic hip joint components may betested to determine their respective resonant frequencies. When two ormore hip joint components have the same or similar resonant frequencies,one or more vibrational dampers 120, 140, 160, 180 may be utilized. Itis to be understood that testing of orthopedic components is notrequired as a prerequisite for including vibrational dampers 120, 140,160, 180 as part of an orthopedic hip joint.

Referring to FIG. 5, an exemplary hip implant assembly 200 includes afemoral component 202, an acetabular cup 204, and an acetabular insert206. Due to the presence of high bearing surface forces in total hiparthroplasty, the femoral component 202 may be totally or partiallyfabricated using highly magnetic materials that work in conjunction withhighly magnetic materials that may be used to fabricate the acetabularcup 204 and/or acetabular insert 206 to reduce lower hip joint forcesand/or hip separation.

In this exemplary embodiment, the femoral component 202 includes afemoral stem 208 that is adapted to be implanted into the femoralintramedullary canal after the femoral bone has been properly resected.Extending proximally from the femoral stem 208 is an integral neck 210that includes a threaded or conical end (not shown) adapted to receive afemoral ball 214. The femoral ball 214 is fabricated to include abiologically compatible metallic coating (e.g., stainless steel,titanium, titanium alloy), which surrounds a neodymium magnetic core orother ferrous core. Alternatively, the femoral ball 214 may befabricated to include one or more permanent magnets (e.g., neodymiummagnet) embedded within a biologically compatible metal substrate (e.g.,stainless steel, titanium, titanium alloy). In either circumstance, themagnetic field generated by the femoral ball 214 represents a magneticNorth Pole, which is pulled toward any magnetic South Pole.

In order to retard dislocation of the femoral ball 214 from theacetabular insert 206, the acetabular cup 204 includes a biologicallycompatible metallic coating 220 (e.g., stainless steel, titanium,titanium alloy), which surrounds a ferrous core. Alternatively, theacetabular cup 204 may be fabricated to include one or more magnetsembedded within a biologically compatible metal substrate (e.g.,stainless steel, titanium, titanium alloy). In either circumstance, themagnetic field generated by the acetabular cup 204 represents a magneticSouth Pole. Because the force between the North Pole and the South Poleis inversely proportional to the square of the distance between themagnetized surfaces, it is important to reduce the distances between thePoles.

In order to reduce the distances between the poles, the acetabularinsert 206 may be fabricated using two considerations. First, theacetabular insert 206 may be fabricated to have a minimal thickness,thereby reducing the distance between the femoral ball 214 and theacetabular cup 204. Alternatively, or in addition, the acetabular insert206 may itself house one or more magnets oriented so that the North Polefaces toward the acetabular cup 204 and the South Pole faces toward thefemoral ball 214. In exemplary form, an acetabular insert 206 includes abowl-shaped neodymium magnetic core or other ferrous magnetic core. Thiscore is then overmolded or encapsulated in a biologically compatiblepolymer or ceramic to form a capsule 226 comprising the bearing surfaceof the cup 204. In exemplary form, the mean thickness of the capsule 226is between 0.1 mm to 20 mm.

Referring to FIG. 6, an alternate exemplary hip implant assembly 240includes a femoral component 242, an acetabular cup 244, and anacetabular insert 246. The femoral component 242 includes a femoral stem248 having an integral neck 250 that includes a threaded or conical end(not shown) adapted to receive a femoral ball 254. The femoral ball 254is fabricated to include a biologically compatible metallic coating(e.g., stainless steel, titanium, titanium alloy), which surrounds aneodymium magnetic core or other ferrous core. Alternatively, thefemoral ball 254 may be fabricated to include one or more permanentmagnets (e.g., neodymium magnet) embedded within a biologicallycompatible metal substrate (e.g., stainless steel, titanium, titaniumalloy). In either circumstance, the magnetic field generated by thefemoral ball 254 represents a magnetic North Pole.

In order to decrease impact forces between the femoral component 242 andthe acetabular components 244, 246, the magnetic field of the femoralcomponent and the acetabular components may be the same. Specifically,at least one of the acetabular insert 246 and the acetabular cup 244includes a biologically compatible metallic coating 260 (e.g., stainlesssteel, titanium, titanium alloy), which surrounds a ferrous core.Alternatively, the acetabular cup 244 and acetabular insert 246 may befabricated to include one or more magnets embedded within a biologicallycompatible metal substrate (e.g., stainless steel, titanium, titaniumalloy). In. either circumstance, the magnetic field generated by theacetabular cup 244 and acetabular insert 246 represents a magnetic NorthPole. Because the North Poles of the femoral component 242 and theacetabular components 244, 246 operate to repel one another, the impactforces between the femoral component and the acetabular components maybe reduced.

Turning to FIG. 7, another alternate exemplary hip implant assembly 270includes a femoral component 272, an acetabular cup 274, and anacetabular insert 276. The femoral component 272 includes a femoral stem278 having an integral neck 280 that includes a threaded or conical end(not shown) adapted to receive a femoral ball 284. In this embodiment,the femoral ball 284 and the most proximal aspect 286 of the acetabularcup 274 (farthest from the femoral shaft) both have a positive polarity(i.e., North Pole), but a distal medial 288 and distal lateral aspect290 of the acetabular cup 274 have a negative polarity (i.e., SouthPole). In exemplary form, the positive-positive polarity interactionoperates to decrease the compressive forces during weight-bearingactivity, while the positive-negative polarity interaction resistsdislocation and femoral ball separation.

Referencing FIGS. 8 and 9, an additional exemplary orthopedic hip joint300 comprises a cup component 302 and a femoral component 304 havingconcentric spheres. More specifically, the patient's anatomy is preparedto ensure both the cup component 302 and a femoral component 304 have acommon spherical center with respect to the acetabulum.

Referring to FIGS. 10-13, although it has been stated in numerouspublications that the human hip is a revolute joint, whereas only threesequential rotations are present, the actual shapes of the acetabulumand femoral head of the femur are not pure spheres. In fact, theposition of numerous exterior points on the acetabulum and the femoralhead can be recorded and computer algorithms applied to these points tocreate spheres whose surface best correlates with the recorded points.In a study conducted by the inventor, it was determined that numerousspheres can be derived using sets of points on the surface of theacetabulum and the femoral head. Therefore, in a conservative sense,using sets of points on the acetabulum and on the femoral head, onecould easily derive at least fifty spheres for each of the acetabulumand the femoral head that at least partially correlated with therecorded points (i.e., at least some of the recorded points wouldcomprise an exterior point on a sphere). Therefore, if fifty spheres forthe acetabulum and fifty spheres for the femoral head were chosen, thiswould result in twenty-five hundred combinations of spheres. But theinventor has determined that the correct combination of spheres is aconcentric combination derived from the bearing surface interfaces ofthe acetabulum and femoral head during walking, and is derived from thecartilage surface within the acetabulum and the cartilage surface on thefemoral head.

Referring back to FIGS. 8 and 9, in order to design the cup component302 and the femoral component 304, a kinematic analysis is conducted forthe intended recipient of the orthopedic hip joint 300. This kinematicanalysis defines points on recipient's natural femoral head in contactwith the acetabulum and corresponding points on the acetabulum incontact with the femoral head.

An exemplary kinematic analysis is performed to determine these sphereswhile the joint is under dynamic, weight-bearing, in vivo conditions.During normal gait motion, these spheres maintain concentricity.Therefore, with present imaging technology, fluoroscopy is an exemplarymethod of use. But other imaging modalities, like ultrasound could beused to perform the kinematic analysis. Under fluoroscopic surveillance,the patient performs normal walking. Then, the patient undergoes asecond clinical imaging test using CT, MRI, or ultrasound (othertechnologies could also be used). In the context of a CT scan, thescanned slices of the joint are used to create a three dimensional (3D)model of the patient's pelvis and femoral bones. Then, these 3D bonesare overlaid onto the two dimensional fluoroscopic images. Once all ofthe fluoroscopic images, or a selected chosen few fluoroscopic imagesare converted to 3D, the patient's hip motion may be viewed in anychosen plane. Using a collision detection analysis, the point of thefemoral head in contact with the pelvis and the points of the pelvis incontact with the femoral head are determined and mapped sequentially.

If one does not have the capability to determine the correct points onthe acetabulum and the femoral head using the above mentioned kinematicanalysis, one may alternatively use trial and error to derive thelocation of the concentric spheres by placing different sizes of spheresin different locations relative to the acetabulum and the femoral headfor each patient until the spheres are concentric in multiple planes.Once the anatomical concentricity is established for that particularpatient, the location can be mapped and relocated during surgery toensure that the spherical centers of the implanted components arematched to the anatomical spherical centers.

Referring to FIGS. 14-17, spheres are superimposed onto the points thatbest conform to the mapped points on the pelvis and femoral head tocreate individual spheres. It is important to note that these spheresmay be derived using the boney anatomy or on the cartilage. The correctsphere for each patient may be dependent on the quality of cartilageand/or the concentricity of the two spheres.

After the spheres are defined, the location of the center of thesespheres is defined and used a target origin (or center) for the spheresof the implanted femoral head and the acetabular cup. The center of twoderived spheres can be defined quite easily using numerous softwarepackages and/or using a mathematical approach. It is important to thenmap out the location of the patient's anatomical sphere centers withrespect to boney landmarks. The center of the chosen pelvis sphere needsto be tracked with respect to boney landmarks on the pelvis and thecenter of the femoral head sphere needs to be tracked with respect toboney landmarks on the femur bone.

Preparation of the bones to receive prosthetic components should be donewith respect to maintaining the patient's anatomical spheres. Therefore,after the bones have been prepared for the implanted components, theimplanted components are implanted to maintain these spherical centers.Alternatively, a surgical navigation system or an imaging modality maybe used to locate the patient's spherical center(s) and ensure that theimplanted components are implanted to maintain the spherical center(s).

Unlike the foregoing exemplary embodiment that is patient-specific, costconsiderations may require a finite set of implant components thatdiffer in size from one another. This finite set of implant componentsmay include gender and ethnicity considerations, depending upon thepopulation utilized to model the implant components. By doing so, it isanticipated that there will be more than three acetabulum spheres(presently, patients normally received a femoral head having either a 28or 32 or 36 mm sizing) needed to fit everyone requiring a TKA. Then,knowing the proper acetabulum sphere sizes, the center of these spheresis defined and used to develop proper sizing for the acetabular cup, cupinsert, and femoral ball/head components. Proper sizes for theacetabular cup, cup insert, and femoral ball/head are designed tomaintain spherical concentricity throughout normal gait.

Maintaining proper spherical centers also leads to the femoral stembeing implanted properly so that the center of femoral head sphere islocated at the origin of the acetabular cup sphere. The centers for bothof these spheres (head and cup) are thus coincident with the anatomicalcenter of the acetabulum sphere taking into account the cartilagesurface.

It is understood that in most sizing analysis of implants, if a bellcurve is used, there is a set number of sizes that will include 90% ofthe subjects requiring that type of implant. Unfortunately, in a totalhip arthroplasty (THA), unlike other prosthesis, such as a total kneearthroplasty (TKA), all patients receive one of three sizes. Therefore,in a perfect world, the best outcome would be that 30% of the patientsreceive a THA implant that may maintain concentric spheres.Unfortunately, this is not the case because a slight misalignment of theimplanted components will lead to the pelvis and femoral head spheresnot being concentric. Therefore, it is important to understand andderive proper spheres that allow at least 90% of the population toreceive a THA with the ability to maintain their anatomic sphereconcentricity. Using an exemplary kinematic analysis as discussedpreviously herein, one determines spherical sizes for the pelvis andspherical sizes for the femoral head that fit a predetermined percentageof patients. Although present day sizes are only 28, 32 and 36 mmfemoral heads that are then mated with the acetabular cup liner, thisanalysis may reveal that 10 to 12 sizes of femoral heads and acetabularcup liners should be produced so that 90% of the subjects under the bellcurve could receive proper femoral head and acetabular cup sizes thatmaintain their spherical concentricity. These sizes may not be wholenumbers, but rather decimal numbers. Again, it is important that eachpatient receive a femoral head and acetabular component that maintainsspherical concentricity after THA implantation. Using the wrong femoralhead and/or acetabular cup insert size leads to these implanted spheresnot being concentric with the patient's anatomical sphericalconcentricity. This improper sizing may lead to the inducement of shearforces, further leading to femoral head separation and/or dislocation.

The shape of present day femoral stems is not able to accommodatespherical concentricity due to limited options. Therefore, it isunderstood that multiple neck lengths and neck angles with respect tothe femoral stem may be available to the surgeon. Therefore, once theanatomical spherical center is found, it may be relocated using thespherical centers of the implanted components by utilizing various stemneck options. This may be of particular concern in case where a surgeonremoves too much or not enough bone and/or the femoral cut and/or thestem is fixated into the femoral bone at an offset angle.

Referring to FIGS. 18 and 19, femoral head separation in present-day THAis induced by the acetabular cup and the femoral head being implanted ina position and/or orientation that does not coincide with the properspherical center of patient. Thus, this misplacement of these componentsinduce shear forces so that the patient's muscular structure attempts torealign the prosthetic components to the patient's proper anatomicalspherical center. FIGS. 18 and 19 show examples of present-day implantsthat were implanted and how these implants have not maintained thepatient's proper anatomical spherical center. The dotted circlerepresents the implanted femoral head sphere for this patient. The halfdot represents the center of this implanted femoral head sphere. Thesolid circle represents the anatomical acetabulum sphere derived fromthe weight-bearing contact points, on the cartilage, for this subjectduring normal walking. The solid dot represents the center of thisanatomical based acetabulum sphere. Unfortunately, after implantation,the femoral head is no longer rotating around this patient's anatomicalspherical center. But the patient's muscular structure around the hipjoint is wed to this anatomical spherical center and attempts to rotatethe hip implant around this patient's anatomical spherical center.Because the patient's anatomical sphere center and prosthetic spherecenters (for ball and socket) are not coincident, shear forces arecreated in the implanted hip joint that lead to hip separation and/orhip dislocation.

As shown in FIGS. 20 and 21, the patient's native anatomy includes anacetabulum 510 in the pelvis 512 that is adapted to receive femoral head514 at the proximal end of the femur 516, so the femoral head isreceived within a cavity defined by the acetabulum to form a ball andsocket joint. In a patient's native hip joint, the acetabulum 510defines a cavity having a spherical center that is concentric with thespherical center of the femoral head 514. As the femoral head 514 pivotswith respect to the acetabulum 510, this common spherical centerorientation is maintained. But preexisting orthopedic hip joints do notmaintain this common spherical center orientation between the cavity ofthe acetabulum and the femoral head.

An exemplary approach for determining and maintaining this commonspherical center orientation uses human anatomical landmarks, such asthe femoral head ligament 520. The femoral head ligament 520 is a majorconstraint that is currently removed without any attempt by the surgeonto utilize its location to define cup orientation. In contrast, thisexemplary technique includes retention of certain features of theacetabulum before an instrument may be used to define the location ofthe femoral head ligament.

Referring to FIG. 22, a landmark cup or jig 530 includes an orifice 532sized accommodate a portion of the femoral head ligament 520 thatremains attached to the acetabulum 510. In this exemplary embodiment,the landmark cup 530 is bowl-shaped and includes a plurality of tabs534. Each tab 534 includes a through hole 536 that corresponds to thelocation of a fastener used to secure an acetabular cup to the pelvis512.

Referencing FIG. 23, the landmark cup 530 is positioned over theacetabulum 510 so that the orifice 532 overlies the location of thefemoral head ligament 520. The orifice 532 may take on various sizes andvarious positions within the cup 530 to mark the location of the femoralhead ligament and may be used on multiple patients having variablefemoral head ligament locations in the acetabulum. More specifically,after the orifice 532 is positioned to overlie the femoral head ligament520, the cup 530 is pushed against the acetabulum 510, with the femoralhead ligament extending through the orifice. Thereafter, holes aredrilled into the pelvis 512 using the tab holes 536 as guides.

It should be noted, however, that while the landmark cup 530 isgenerally in the shape of an acetabular cup, this shape is not critical.The cup 530 may be any shape, such as circular, elliptical, square,rectangular, etc., and could be of any size. What is critical isretention of at least one of the anatomical reference points associatedwith the acetabulum 510 so that mounting locations and/or acetabular cuporientation can be established prior to reaming of the acetabulum.

Referring to FIG. 24, after the holes in the pelvis 512 are drilled,pins 560 are inserted into the holes. The landmark cup 530 is alsoremoved, which allows for this same orientation to be utilized later inthe surgery for reaming and permanent acetabular cup 570 positioning(see FIG. 29).

Referencing FIG. 25, the pins 560 remain in the pelvis 512 after thelandmark 530 is removed. Thereafter, as shown in FIG. 26, the acetabulum510 is prepared to receive the permanent acetabular cup 570 (see FIG.29).

Referring to FIGS. 26 and 27, it is currently difficult for the surgeonto properly ream out the acetabulum so the acetabular cup and cup insertare positioned correctly. To help the surgeon properly ream out theacetabulum, after the landmark cup 530 has been removed, a guide pin cup580 is secured to the acetabulum using the pins 560 that extend throughcorresponding openings in the guide pin cup. The guide pin cup 580includes an opening exposing a portion of the acetabulum where thefemoral head ligament is located. After the guide pin cup 580 is inposition, a guide pin 582 is secured to the acetabulum at the center ofthe socket, referenced with respect to the femoral head ligament, and/orother bone or soft-tissue landmarks. This guide pin 582 may be 1.0 cm to20 cm in length and have diameter from 0.1 cm to 3.0 cm, for example.The guide pin 582 may be fabricated from numerous materials such as,without limitation, cobalt chrome, steel, titanium, tantalum, andceramics. Thereafter, the guide pin cup 580 is removed from over top ofthe guide pin 582 and the ancillary pins 560, which leaves the guide pin582 mounted to the acetabulum. Using the guide pin 582 and the ancillarypins 560 on the pelvic bone, a reamer (not shown) is inserted in thesocket and the acetabulum is reamed uniformly and in the correctdirection to create a revised acetabulum 510′ (see FIG. 27). Afterreaming, the reamer and guide pin 560 are both removed, while theancillary pins 560 are retained to guide the implanted cup into thesocket.

Referring to FIG. 28, the permanent acetabular cup 570 is inserted intothe revised acetabulum 510′ using the guide pins 560 so as to maintainthe proper orientation necessary to produce concentricity with thefemoral head.

Referring to FIG. 29, after the acetabular cup 570 is securely in placewithin the revised acetabulum 510′, the guide pins 560 are removed andthe corresponding holes filled.

Referring back to FIG. 20, during weight-bearing gait, the femoral headligament 520 remains taught so that the ligament distance throughout theweight-bearing portion of the gait cycle remains constant. The locationof the femoral head ligament 520 attachment site in the acetabulum 510is identified as point A. The location of the femoral head ligamentattachment 520 site on the femoral head 514 is identified as point B,Therefore, if the line constructed from point A to point B is constantthroughout the weight-bearing portion of the gait cycle, then one mayuse this line to define the location of the proper acetabulum sphere.Since points B and C are on the same bone, a fixed body, then thedistance from points B to C is always constant. Therefore, by knowingthe distances from points A to B and B to C, one may construct a linefrom point A to point C, which is also a constant. Although thisanalysis is planar in nature, a fourth out-of-plane point may be used toalign the longitudinal direction of the cup. By identifying the locationof the femoral head ligament 520 in the acetabulum 510, prior to theacetabulum being prepared during surgery, the distance from the femoralhead ligament 520 to the spherical center of the acetabular cup 570 (seeFIG. 29) and the femoral head 514 is measured to ensure that the properspherical center has been maintained. The femoral head ligament 520 isthe only landmark within the acetabulum 510 that can be used to definethe location of the proper spherical center. Knowing the distance fromthe femoral head ligament 520 attachment site, within the acetabulum 510to the proper spherical center is crucial to the surgical alignment andimplantation of the acetabular cup 570 and femoral head 514.

Although the example just described may be used to define concentricspheres during surgery, one could use a number of methodologies tolocated and/or maintain concentric spheres post THA. In an exemplarysimplistic methodology, one could attempt to define and maintainconcentricity using static x-rays, but this method would be intwo-dimensions and may not properly define concentricity inthree-dimensions. This method may only allow one to define similarcircular centers. One could also use pre-operative planning and/orimaging, such as MRI, CT scans, ultrasound and/or any other imagingmodality. Most of the imaging modalities that can presently be used arestatic and may subject the patient to radiation exposure. One could alsouse intra-operative surgical navigation and/or imaging modalities tolocate and/or maintain concentric spheres. Most importantly, it isimportant to ensure that proper cup and femoral stem orientation ischosen to ensure concentric spheres post THA surgery.

Referring to FIG. 30, all present-day THA surgeries require removal ofthe femoral head ligament 602. But this exemplary embodiment of aprosthetic hip joint retains the femoral head ligament 602 if it ishealthy. As stated previously, the femoral head ligament 602 is astabilizing mechanism in the hip joint that couples the pelvis 603 tothe femur 605.

If the femoral head ligament 602 is not healthy, an artificial structuremay be used to reinforce the femoral head ligament. This artificialstructure may be comprised of any number of materials such as, withoutlimitation, twine, silicone rubber, elastic silicone rubber, guttapercha, saline rubber, gore-tex, polystyrene, polytetrafluoroethylene,nylon, polyethylene, polyester, silk, polyethylene teraphthalate, andpolyvinyl alcohol-hydrogel. This material may be wrapped around thefemoral head ligament 602, attached to the base of the femoral headligament attachment site in the acetabulum, inter twined within thefemoral head ligament, or used in another manner to reinforce thestrength of the femoral head ligament.

Referencing FIGS. 30 and 31, initially, the femoral head 604 is severedfrom the remainder of the femur 605. A cutting instrument (not shown) isthen used to shape a bone segment 610 from the femoral head 604, wherethe bone segment remains attached to the femoral head ligament 602. Inexemplary form, the bone segment 610 is cut into a cylindrical shapehaving the same length as the native femoral head 604, with one end ofthe cylinder being mounted to the femoral head ligament 602. It shouldbe noted that the cylindrical shape is not critical and other shapes andsizes such as, without limitation, rectangular, triangular, and roundedmay be utilized as part retaining the bone segment.

Referring to FIGS. 32-34, the exemplary prosthetic hip joint 600comprises an acetabular cup 620 and an acetabular cup liner 622 eachhaving a through orifice (not shown) that is sized to allow throughputof the femoral head ligament 602 and the bone segment 610. The exemplaryprosthetic hip joint 600 also comprises a femoral ball 628, a femoralneck 630, and a femoral stem 632, where the femoral neck is integrallyformed with the femoral stem. The femoral ball 628 includes a throughhole (not shown) that is sized to allow insertion of the bone segment610 so the portion of the bone segment to which the femoral headligament is mounted is substantially flush with the exterior arcuatesurface of the ball. The neck 630 includes a cavity 636 axially alignedwith the through hole in order to receive a portion of the bone segment610. In this exemplary embodiment, the cavity 636 is cylindrical.

Referring to FIGS. 32-34, implantation of the exemplary prosthetic hipjoint 600 includes utilizing a cutting instrument to create a bonesegment 610 that is mounted at one end to the femoral head ligament 602and free at an opposing end. The femoral head ligament 602 during thisprocess remains attached to the pelvis 603. After the bone segment 610is cut, the bone segment and a portion of the femoral head ligament 602are thread through the through orifice of the acetabular cup 620. Theacetabular cup 620 is then mounted to the pelvis 603. The bone segment610 and a portion of the femoral head ligament 602 are next threadthrough the through orifice of the acetabular cup liner 622. Theacetabular cup liner 622 is then mounted to the acetabular cup 620.Then, the bone segment 610 is thread through the through hole of thefemoral ball 628 so that the end of the bone segment mounted to thefemoral head ligament 602 is substantially flush with the bearingsurface of the femoral ball. And at least a portion of the remainingbone segment 610 not received within the femoral ball 628 is receivedwithin the femoral neck cavity 636.

The bone segment 610 may be attached to the femoral neck 630 usingnumerous methodologies and techniques. An exemplary method for use withthe instant exemplary embodiment 600 includes applying bone cement inbetween the bone segment 610 and the wall(s) of the femoral neck 630that delineate the cavity 636. Another exemplary method includesinterposing bone ingrowth material between the bone segment 610 and thewall(s) of the femoral neck 630 that delineate the cavity 636.

The femoral ball 628 may alternatively be tapered to create a cap-likeindentation at the site where femoral head bone is received. Thelocation on the femoral ball 628, where the femoral head bone isreceived thus does not have to be tapered and does not have be acylindrical hole. In other words, the cavity on the femoral ball 628 toreceive the modified femoral head bone may be any of a number of shapes.

The amount of bone retained from the femoral head bone may be of anysize and shape. The length of this retained femoral head bone may belong enough to be fixated within only the femoral ball 628, or it can belonger to insert through the femoral ball and into the femoral neck 630of the femoral prosthesis. Alternatively, the retained femoral head bonemay be long enough so that the distal end of the bone can pass throughthe femoral ball 628, through the femoral neck 630, through a portion ofthe femoral stem and into or through the femoral shaft 632. Thistechnique may allow the blood supply to be maintained within theretained femoral head bone and the femoral head ligament, thus allowingthe retained femoral head bone to grow into the femur.

Referring to FIG. 35, an alternate exemplary embodiment 700 is the sameas the foregoing prosthetic hip joint 600, except for the addition ofsutures or other retention lines 702 extending between at least two ofthe acetabular cup, acetabular cup liner, the femur, the femoral neckand the pelvis. These sutures or retention lines 702 may be utilizedlike suspenders, wrapping around the acetabular cup, between the cup andthe bone and then either attaching to the femoral implant component orto the femoral bone. The acetabular cup may include grooves 704 to allowthe sutures or other retention lines 702 to fit between the cup and thebone and then be securely cemented to the implant and the bone or allowfor the bone to grow into the cup and/or the artificial structure.

Referencing FIGS. 36-38, an exemplary mobile bearing acetabularcomponent 800 comprises an acetabular cup 802 and a repositionable cupinsert 804. The repositionable cup insert 804 includes a semicircularrib 806 having a dove tail cross-section that extends circumferentiallyon the cup insert's exterior surface. This rib 806 is adapted to be atleast partially received within a corresponding semicircular groove 808formed on the interior of the cup 802. In this exemplary embodiment, thegroove 808 takes on a dove tail shape. It should be noted, however, thatother rib 806 and groove 808 shapes may be utilized such as, withoutlimitation, the rib 806 having a T-shape and the groove 808 having acorresponding cavity to receive and retain the rib. Moreover, it iswithin the scope of the disclosure for the rib 806 to be located on theinterior of the acetabular cup 802, while the groove 808 is locatedcircumferentially on the cup insert 804.

In this exemplary embodiment, during weight-bearing activities, the cupinsert 804 is locked and cannot slide and/or extend and remains in afixed orientation with respect to the cup 802. During non weight-bearingactivities, especially those that contribute to dislocation, the cupinsert 804 is allowed to translate along one axis. Specifically, the rib806 is repositionable within the groove 808, thereby allowing the cupinsert 804 to translate along one axis with respect to the cup 802.Therefore, pre-operatively, if preferred, one may determine the correctcup 802 orientation so that the cup insert 804 will perfectly translatealong an axis that the patient normally uses to perform the activitiesthat cause femoral head dislocation. The cup insert 804 slides and/orextends in both directions along that chosen axis. Thus, when thepatient performs non-weight bearing tasks, the cup insert 804 extendsoutside of the acetabular cup 802, ensuring that the femoral head doesnot dislocate. This cup insert 804 may have full freedom to translateand/or rotate along one axis within the cup 802 or the cup insert 804may be constrained with some stopping and/or locking mechanism. Thisstopping and/or locking mechanism may constrain the translation ineither direction and allow differing amounts of translation for eachpatient, depending on the amount of translation needed for each patient.

Referring to FIGS. 39 and 40, a second exemplary mobile bearingacetabular component 840 comprises an acetabular cup 842 and arepositionable cup insert 844. The repositionable cup insert 844includes a semicircular rib 846 having a dove tail cross-section thatextends circumferentially on the cup insert's exterior surface. This rib846 is adapted to be at least partially received within a correspondingsemicircular groove 848 formed on the interior of a semicircular track(not shown). In this exemplary embodiment, the groove 848 takes on adove tail shape. It should be noted, however, that other rib 846 andgroove 848 shapes may be utilized such as, without limitation, the rib846 having a T-shape and the groove 848 having a corresponding cavity toreceive and retain the rib. Moreover, it is within the scope of thedisclosure for the rib 846 to be part of the track, while the groove 848is located circumferentially on the cup insert 844.

Another way for this implant to achieve translation in two directions isto include an intermediate liner 851 (see FIG. 39) that fits between theacetabular cup 842 and the insert liner 844. This intermediate liner 851can be polyethylene, metal, ceramic or any other bearing surfacematerial. The intermediate liner 851 allows for the insert liner 844 totranslate along one direction with respect to the intermediate liner,while the intermediate liner 844 translates along a second direction(e.g. perpendicular to the first direction) within the acetabular cup842.

In this exemplary embodiment, the liner 851 includes a projection 852formed on its circumferential exterior that is received within acorresponding semicircular groove 854 formed on the interior of the cup842. In this exemplary embodiment, the groove 854 takes on a dove tailshape. It should be noted, however, that other projection 852 and groove854 shapes may be utilized such as, without limitation, the projection852 having a T-shape and the groove 854 having a corresponding cavity toreceive and retain the projection. Moreover, it is within the scope ofthe disclosure for the projection 852 to be located on the interior ofthe acetabular cup 842, while the groove 854 is located on thecircumferential exterior of the track 850.

The semicircular track 850 in FIG. 39 is rotationally offset ninetydegrees from the groove 854 on the interior of the circumferential cup842. It should be noted, however, that the track 850 need not be offsetto precisely ninety degrees and may be offset at a variety of angles. Inthe manner shown in FIG. 39, the cup insert 844 may slide toward an eastor west direction with respect to the semicircular track 850 and withrespect to the acetabular cup 842, thereby sliding the cup insert in aneast or west arcuate direction. At the same time, the track 850 mayslide toward a north or south direction with respect to the acetabularcup 842, thereby sliding the cup insert 844 in a north or south arcuatedirection. In other words, the net result is that there are two degreesof freedom for net movement of the cup insert 844 with respect to thecup 842. A first degree of freedom is an arcuate motion in a north orsouth direction, and the second degree of freedom is an arcuate motionin an east or west direction, where the degrees of freedom areindependent of one another any may be exercised individually or intandem.

Referring to FIG. 41, a third exemplary mobile bearing acetabularcomponent 870 comprises an acetabular cup 872 and a repositionable cupinsert 874. The repositionable cup insert 874 includes a semicircularrib 876 having a dove tail cross-section that extends circumferentiallyon the cup insert's exterior surface. This rib 876 is adapted to be atleast partially received within a corresponding semicircular groove 878formed on the interior of a semicircular track 880. In this exemplaryembodiment, the groove 878 takes on a dove tail shape. It should benoted, however, that other rib 876 and groove 878 shapes may be utilizedsuch as, without limitation, the rib 876 having a T-shape and the groove878 having a corresponding cavity to receive and retain the rib.Moreover, it is within the scope of the disclosure for the rib 876 to bepart of the track 880, while the groove 878 is located circumferentiallyon the cup insert 874.

In this exemplary embodiment, the semicircular track 880 includes aprojection 882 formed on its circumferential exterior that is receivedwithin a corresponding semicircular groove 884 formed on the interior ofthe cup 872. In this exemplary embodiment, the groove 884 takes on adove tail shape. It should be noted, however, that other projection 882and groove 884 shapes may be utilized such as, without limitation, theprojection 882 having a T-shape and the groove 884 having acorresponding cavity to receive and retain the projection. Moreover, itis within the scope of the disclosure for the projection 882 to belocated on the interior of the acetabular cup 872, while the groove 854is located on the circumferential exterior of the track 850.

The semicircular track 880 is rotationally repositionable with respectto the groove 884 on the interior of the circumferential cup 872. Inthis manner, the cup insert 874 may slide toward an east or westdirection with respect to the semicircular track 880 and with respect tothe acetabular cup 872, thereby sliding the cup insert in an east orwest arcuate direction. In addition, the cup insert 874 is rotatablewith respect to the acetabular cup 872 in 360 degrees. At the same time,the track 880 may slide toward a north or south direction with respectto the acetabular cup 872, thereby sliding the cup insert 874 in a northor south arcuate direction. In other words, the net result is that thereare three degrees of freedom for net movement of the cup insert 874 withrespect to the cup 872. A first degree of freedom is an arcuate motionin a north or south direction, a second degree of freedom is an arcuatemotion in an east or west direction, and a third degree of freedom isaxial rotation, where the degrees of freedom are independent of oneanother any may be exercised individually, at once, or in tandem.

Another manner for this implant 870 to achieve translation and rotationcould be through the use of an intermediate liner 890 that rotatesfreely with respect to the acetabular cup 872, but includes a groove 892that allows the cup insert 874 to freely translate along one direction.Since the intermediate liner 890 can freely rotate, the direction of theinsert liner translation may be in any direction with respect to theacetabular cup 872 and/or the patient's natural anatomy.

Although most THA acetabular cups are designed to be a sphere, the cupmay alternatively be elliptical allowing for the insert to translateand/or rotate to a greater amount, if deemed necessary.

Referring to FIG. 42, an exemplary process for use with hip jointsurgery includes removing the native femoral head 900 of a patient toreshape the neck of the femoral neck bone. After the femoral head isremoved, an implanted femoral head is inserted into and/or around thereshaped femoral neck bone, resembling an implanted hip stem and femoralhead. While the shaped femoral head 900′ is shown as having acylindrical shape, it should be understood that the femoral head may beshaped in a rectangular, spherical, cylindrical, trapezoidal, or anotherother shape that could be beneficial for attaching a femoral ball 902 tothe native bone. Although not shown in this figure, the femoral head mayhave a stem that inserts into the femoral neck bone. Also, the fullfemoral head bone anatomy does not have to be removed and the implantedfemoral head may be attached onto the femoral head bone.

Referencing FIG. 43, another exemplary process for use with hip jointsurgery includes removing or reshaping the native femoral head 900 of apatient to resemble the neck of a prosthetic femoral component.Thereafter, a metal, ceramic or any other implantable materialcylindrical sleeve 910 is positioned to circumscribe the reshaped bone900′ (see FIG. 42) for stabilization. After the sleeve 910 is mounted tothe reshaped femoral head 900′, a prosthetic femoral ball 902 is mountedto the reshaped femoral head and/or femoral neck.

Referring to FIG. 44, a further exemplary process for use with hip jointsurgery includes removing and/or reshaping the native femoral headand/or neck 900 of a patient to resemble the neck of a prostheticfemoral component. In this exemplary process, the femoral head 900 isreshaped and a trapezoidal sleeve 920 is positioned to circumscribe thereshaped bone for stabilization. After the sleeve 920 is mounted to thereshaped femoral head, a prosthetic femoral ball 922 is mounted to thereshaped femoral head.

In the foregoing exemplary processes of FIGS. 42 and 43, it is alsowithin the scope of the disclosure that the sleeve 910, 920 and thefemoral ball 902, 922 comprise a single, integral component. Likewise,the femoral head can slide over the bone and/or the femoral sleeve, orit can also have an internal like stem that could go into the bone ofthe femur. It should also be noted that while the femoral head andfemoral sleeve are shown as two separate pieces, the femoral head andfemoral sleeve may also be one piece and/or modular to allow for theseaspects to be attached creating one secure piece.

Referring to FIGS. 45-49, a surgeon improperly reaming out theacetabulum may lead to the placement of the acetabular cup at a locationnot allowing for concentricity with the femoral head of the femoralimplant. Since concentricity of these components is essential tominimize or eliminate both hip dislocation and/or femoral headseparation, an irregular acetabular cup or cup insert may be required toaccommodate for the improper reaming. Specifically, the exemplaryirregular acetabular cup or cup insert 1000 does not have uniformity inwall thickness, radius and/or shape. This non-uniformity of either theacetabular cup and/or cup insert allows for spherical center realignmentto ensure concentricity between the acetabular cup and femoral headcenters.

Referring to FIG. 45, present day acetabular cups 1100 all have auniform wall thickness.

Referencing FIGS. 46-48, if a surgeon reams out too much bone from oneor more regions (e.g., points A-E in FIG. 46) of the acetabulum, thenthe surgeon can use a non-uniform acetabular cup and/or cup insert 1000,1002, 1004. The non-uniform acetabular cup and/or cup insert 1000, 1002,1004 has a non-uniform shape and wall thickness. The non-uniformity isused to shift the spherical center in various directions, such as,without limitation, proximal, distal, medial, and lateral. In thismanner, the spherical center of the femoral component is aligned withthe spherical center of the acetabular component.

Referring to FIG. 49, the surgeon who reams out too much bone from theacetabulum may need a spacer 1010 that allows for the center of theacetabular cup or cup insert 1100 to be repositioned into alignment.This spacer 1010 may be mounted to the front side or back side of theacetabular cup and/or cup insert 1100. And the spacer 1010 may have auniform of non-uniform wall thickness and shape. The spacer 1010 may beof any shape necessary to shift the spherical center in the properdirection. Exemplary materials for fabricating the spacer 1010 include,without limitation, titanium, cobalt chromium, high densitypolyethylene, and stainless steel.

Referencing FIGS. 46-49, if the surgeon reams away too much bone in theregion between points A and B, B and C, C and D or A and D of FIG. 46,the surgeon may use either a non-uniform acetabular cup or cup insert1000, 1002, 1004 or a spacer 1010 to shift the acetabular cup sphericalcenter to the desired direction. It is also within the scope of thedisclosure to use spacers 1010 with one or more of the non-uniformacetabular cup or cup insert 1000, 1002, 1004 to further shift theacetabular cup spherical center to the desired direction.

Though the above exemplary embodiments have all been discussed withrespect to the hip joint, it is also within the scope of the disclosureto apply these same principles to other joints of the body including,without limitation, shoulder joint, elbow joint, and ankle joint. Inother words, the shoulder joint, elbow joint, and ankle joint may beinserted wherever the foregoing describes a hip joint. And those skilledin the art should thus understand that the teachings and embodiments areequally applicable to shoulder joints, elbow joints, ankle joints, andhip joints. Following from the above description and inventionsummaries, it should be apparent to those of ordinary skill in the artthat, while the methods and apparatuses herein described constituteexemplary embodiments of the present invention, the invention containedherein is not limited to this precise embodiment and that changes may bemade to such embodiments without departing from the scope of theinvention as defined by the claims. Additionally, it is to be understoodthat the invention is defined by the claims and it is not intended thatany limitations or elements describing the exemplary embodiments setforth herein are to be incorporated into the interpretation of any claimelement unless such limitation or element is explicitly stated.Likewise, it is to be understood that it is not necessary to meet any orall of the identified advantages or objects of the invention disclosedherein in order to fall within the scope of any claims, since theinvention is defined by the claims and since inherent and/or unforeseenadvantages of the present invention may exist even though they may nothave been explicitly discussed herein.

What is claimed is:
 1. A prosthetic hip joint comprising: a femoralcomponent including a femoral head with a femoral head cavity; and anacetabular component including an acetabular cup and an acetabular cupinsert, the acetabular cup insert and the acetabular cup each having athrough hole, where the through holes overlap a location of a nativefemoral head ligament.
 2. The prosthetic hip joint of claim 1, whereinthe femoral head cavity is sized to receive a portion of a native femurthat remains attached to the native femoral head ligament.
 3. Theprosthetic hip joint of claim 1, wherein the femoral head cavity extendsinto a neck of the femoral component.
 4. The prosthetic hip joint ofclaim 1, wherein the femoral head cavity extends through a neck of thefemoral component and into a shaft of the femoral component.
 5. Theprosthetic hip joint of claim 1, wherein the through holes of theacetabular cup and acetabular cup insert are oriented to align with alocation where a femoral head ligament is mounted to an acetabulum. 6.The prosthetic hip joint of claim 1, wherein the acetabular cup includesa bowl-shaped wall at least partially delineating a concavity, thebowl-shaped wall includes a top perimeter demarcating a first openingthrough the bowl-shaped wall, the bowl-shaped wall also demarcates asecond opening sized to allow throughput of at least a portion of afemoral head ligament.
 7. The prosthetic hip joint of claim 6, whereinthe acetabular cup further includes at least one tab operatively coupledto the wall, wherein the at least one tab includes a through hole. 8.The prosthetic hip joint of claim 6, wherein the acetabular cup furtherincludes a plurality of tabs circumferentially distributed about the topperimeter of the wall, each of the plurality of tabs has a through hole.9. The prosthetic hip joint of claim 6, wherein the acetabular cupincludes a plurality of guide pins each sized to allow insertion intothe through hole of each tab.
 10. A method of mounting an acetabularcomponent to a patient, the method comprising: positioning and aligningan acetabular jig with respect to an acetabulum, where the acetabularjig includes a bowl-shaped wall having a through hole accommodatingthroughput of a portion of a femoral head ligament attached to theacetabulum; drilling reference holes proximate the acetabulum using theacetabular jig as a guide; and inserting a pin into each reference hole;wherein the positioning and aligning step includes inserting the portionof the femoral head ligament attached to the acetabulum through thethrough hole of the acetabular jig.
 11. The method of claim 10, furthercomprising: positioning a guide cup with respect to the pelvis using thepins; mounting a guide pin to the acetabulum while the guide cup is inposition; and removing the guide cup after the guide pin is mounted tothe acetabulum.
 12. A method of implanting at least one orthopedic hipjoint component, the method comprising: implanting and mounting at leastone of an acetabular component to a native acetabulum and a femoralcomponent to a native femur; and maintaining a connection between anative femoral head ligament and at least one of the native acetabulumand the native femur.
 13. The method of claim 12, wherein: theimplanting act includes mounting the acetabular component to the nativeacetabulum; and the acetabular component includes a cup having anorifice through which the native femoral head ligament extends.
 14. Themethod of claim 12, wherein: the implanting act includes mounting thefemoral component to the native femur; and the femoral componentincludes a cavity to receive at least a portion of the native femurconnected to the native femoral head ligament.
 15. The method of claim12, further comprising: reshaping a portion of a native femoral headattached to the native femoral head ligament to create a femoralrevision; implanting and mounting the femoral component to the nativefemur; and coupling the femoral component to the femoral revision. 16.The method of claim 15, further comprising severing the native femoralhead from the native femur, wherein the femoral revision comprises afemoral bone insert, and wherein the act of coupling the femoralcomponent to the femoral revision includes inserting the femoral boneinsert into a cavity of the femoral component.
 17. The method of claim16, wherein the cavity extends into a neck of the femoral component. 18.The method of claim 16, wherein the cavity extends through a neck of thefemoral component and into a shaft of the femoral component.
 19. Themethod of claim 12, wherein: the implanting act includes implanting andmounting the acetabular component to the native acetabulum; and theimplanting act includes implanting and mounting the femoral component tothe native femur.
 20. The method of claim 12, further comprisingmounting a first portion of a tether to at least one of the nativeacetabulum and the acetabular component, and mounting a second portionof the tether to at least one of the native femur and the femoralcomponent.